Chicken Pot Pie

Name: Chicken Pot Pie
Cuisine: American
Ingredients: 1/3 cup margarine; 1/3 cup diced onion; 1/3 cup flour; 1/8 tsp salt; 1/4 tsp pepper; 1 3/4 cups vegetable broth; 1/2 cup oat milk; 1 carton vegan chicken pieces (or 2 cans chicken); 1 heaping cup diced celery; 1 heaping cup frozen peas and carrots; 1 tsp chicken seasoning; 1 pie crust; aluminum foil